This invention relates to the field of halogen element presence sensing and concentration measurement using solid state electrically responsive sensing elements.
An increased current awareness of the dangers attending both prolonged and intense exposure to chemicals in the environment has increased the need for sensitive and easily used detection apparatus. This awareness coincides with the increased popularity of chlorine and other halogen inclusive compounds as cleaning agents, sterilizing agents, chemical reactants, chemical weapons--involving biological and vertabraed object defense, and other industrial reactants. These chlorine and halogen containing materials have been recognized as significant threats to human welfare and, therefore, are deserving of careful precaution in exposure avoidance. Notwithstanding the awareness of potential harm from exposure to these compounds and their constituents, a satisfactory arrangement for measuring worker exposure and determining concentrations of these agents in an atmosphere has been unduly limited by the complexity and cumbersome nature of the heretofore used halogen responsive measurement apparatus. Many currently available chlorine detectors, for example, use the phenomenon of gas adsorption followed by dissolution in an electrolyte which contains bromine ions. A subsequent chemical oxidation reaction with these bromine ions yields an electrical current which has a magnitude that is proportional to the reaction kinetics. A significant limitation of this detector concept, making it inconvenient to use, is the need for a liquid electrolyte in its operation. Periodic replenishment of this electrolyte is essential and, therefore, creates a significant logistics burden which attends use of such instrumentation. In addition to this use burden, it is not possible to make a precise determination of the concentration of chlorine gas in the atmosphere using this detector apparatus since its indication is of a yet or no nature. The integrated solid state detector element is particularly attractive as an improvement on this existing detector technology and is therefore employed in the present invention measuring apparatus.